TITLE: GCN CIRCULAR NUMBER: 39024 SUBJECT: Konus-Wind detection of a bright burst from SGR 1E1841-045 on 2025 January 23 DATE: 25/01/24 17:52:25 GMT FROM: Anna Ridnaia at Ioffe Institute ridnaia@mail.ioffe.ru

A.Ridnaia, D. Frederiks, A.Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report:

A bright burst from SGR 1E1841-045 (IPN triangulation: Svinkin et al., GCN 39022) triggered Konus-Wind at T0=31634.552 s UT (08:47:14.552) on 2025 January 23.

The burst light curve shows a bright pulse, which starts at ~T0-100 ms and has a total duration of ~172 ms. The emission is seen up to ~200 keV.

The Konus-Wind light curve of this burst is available at http://www.ioffe.ru/LEA/SGRs/250123_T31634/

As observed by Konus-Wind, the burst had a fluence of 2.30(-0.07,+0.07)x10^-6 erg/cm2, and a 16-ms peak flux, measured from T0-0.054 s, of 2.02(-0.14,+0.14)x10^-5 erg/cm2/s (both in the 20 - 500 keV energy range).

The spectrum of the burst (measured from T0-0.112 to T0+0.080 s) is best fit in the 20 - 500 keV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha ~ -0.46 and Ep ~ 30 keV.

All the quoted errors are at the 68% confidence level. All the quoted values are preliminary.

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